Sulphonation of aromatic amines



Patented Mar. 3, 1931 I STA P g ARTHUR RMURPHY; or MILWAUKEE ND aosnrnn. oE'son;on-soUTHcMaLwAnxEE;

wrsconsm, ASSIGNORS BY ivrnsnn nssrennnnrsgmo nnwronr on-nmoAL ooR-iPORATION, A CORPORATION on DELAWARE w sunrnonnrron or AROMATIC NoDrawing;

This invention relates to a method for the sulphonation of aromaticamines; whereby aromatic: compounds are pro duced containing group inortho positlon to a sulfonic acid the EIIDI IIO'gI'OU.

Inigeneral; Eilldwing the procedures of r heretoforefknownmethods ofsulfonatin arom'at' 'c; amanes' results 1111116 0111121131011 0 .IIHX-tures I0f= products and 1111 lmany cases 1110011 *siderable destructionlot theoriginal starting '1 material. '1 I In factfihe directsulphonation of:

amines in the: usu'al m'ann'ervdoes not=lead to an ortho sulph'onationIto extent: sufi'icient' tomake theametho-d practical; Recently theretages. :2 c' v the ortho sulfonic acid derivatives of aromati'cuaminesin an economical-1y practicab manner; and thereby render; easilyavailable valuablestarting materials for use in the preparation ,ofotherintermediates and dye- Other and: further important objects 'ofthis inventionwill become apparent from thefollowingdescription-andappended claims;-

Our; present; anethod i makes" it possible to obtainortho' sulfonatedamines in good-yields, and comprises: :treating can aromatic amine withsulf'u'rtri o x'irdeav M The amino body is dissolvent to besuitable'forathe purpose set forth =3 it mustfbe inertrand remainpractically unattacked byzthewsulfurtrl0 1lde1and its boiling is notl'tobepreferred-r: The reaction appears tosproceed; intwo steps, accompaniedin the.

firststep'by thezseparationof an intermediate compel-1nd, presumably the{sulphuricacid f ester .ofthe original amineor! an addition It' istherefore object "ofa our invention td provide-7a method tor thepreparation- "of i solved' in'a suitable dry organic solventthereforsuchas: 'tetrachlo-rethane', carbon tetra-w chloride or 'thelike,"andsubjected to treatmenti with I sulf-ur' trioxid; In order :forthe Application filed January 16, 1928;' Serial Nof247g254;

coni poui id; Thesecond step fcom'prises thezconversion otthecompoundfirst formed into the sulfonic a-cid'derivative. In certain cases y';

thetwo steps appear to takeplace 'SiIIll'illfitII6- ousl-y. p

The following chemical-equation; usin g? las 1 ani example metanylid-ine, probably zrepre sen-tsthe ultimate 'chemical: reaction 1taking :2

.OHae

, Amonsideration of the reaction given'abovew demonstrates clearly oneofthe advantages off? our present process overlthe"heretdfore dewscribed method using :chloro 'sulfonicvacid fas I. 7 0e thesulfonatingiagent; The use ofhloroswlfon'i'c': acid is accompanied bythe: evolution of: r

hydrochloric: acid, which; on account: of lits; highly corrosive nature,m'akesrit necessary to!" i v employ certain precautionary measures inthe design of apparatus to oif'setitsi corrosivecit-v fe'ctsh Theevolution of hydrochloric acid-r: gas alsorin'troduces certaincomplications, Fdue to the fact that :the hydrochloric acid evolvedentrains' some of the-solvent, thus-necessitate r ing an additionalrecovery step which is ac=- companiedwith-further losses of the solvent.lt was therefore quite surprising A20 find that the orthosulpho:aminescouldrbe prepared-dierectly from the amino body by the useof then simple reaction as outlined E above 'and with such an easilyavailable sulfonating-iagentns sulfur;trio'xidea It-is -to :be 'furthernotedythat on-zaccount of the lower" molecular weight of sulfun trioxide compared-'- to chloro sulfonic: acid and onaccount of its lowercost,- I sulfur triolxidepossesses a great economical;advantage 'as'a 1sul-fon'ating agent:

Withoutllimiting our invention-toanypar ticular procedure the following,examp1es,-in which parts by weight-are giy en servevto illustrate thepreferred ,form of our method.

Example lk-12 1" parts ,of new: Xylidihe (1.3 diinethy-l t aminobenzene) are addedto 500 parts of tetrachlorethane. This mass isagitated and there are introduced below the surface 100 parts of sulfurtrioxide, produced by distilling S0 from 60% oleum. During theintroduction of the S0 into the mass, the temperature of thesulphonation mass rises to about 125 C. The mass, which has becomefairly thick as the reaction proceeds, is heated to about 145 C. withrefluxing and held at this temperature for about 3 hours.

- The mass is then poured into 1500 parts of water and neutralized withdilute sodium carbonate solution till the aqueous solution becomesalkaline. The aqueous solution con taining the sodium salt of thesulfonic acid is separatedfrom the tetrachlorethane layer and acidifiedwith about 17 1 parts of 20 Be.

hydrochloric acid. To the acid solution there is now added sufficientsalt to give approximately a 10% salt solution, whereupon the productseparates and after cooling is filtered off. The product is1.3-dimethyl-4-amino-5- sulfo benzene. Some meta Xylidine may berecovered from the tetrachlorethane ayer. The tetrachlorethane may berecovered for reuse by well known methods.

Example 11.-14:3 parts of beta naphthylamine are dissolved in 2000 partsof tetrachlorethane and the mass freed of water by distilling. It isthen cooled to about 18 C.

At this temperature, 90 parts of sulfur trioXide are addedover a periodof about one hour. The mass is stirred for about712' hours and is thenheated to refiuxand stirred at the reflux temperature for about 2 hours.The mass is then cooled, diluted with 1000 parts of water. and madeslightly alkaline with about 60 parts of sodium carbonate. The aqueoussolution is separated from the tetrachlorethane layer and acidified withabout 116 part-s of 20 B.hydr,ochloric acid. 200 parts of common saltare now added and the 1-sulfo-2-amino-naphthalene which separates isfiltered off. Some beta naphthylamine may be recovered from thetetrachlorethane layer.

Other amines such as aniline, para toluidine, para chloroaniline and thelike may be reacted upon in a similar manner to produce sulfo-nic acidcompounds having the sulfonic acid group in ortho position to the aminogroup.

We are aware of v the fact that various changes may be made in thismethod of procedure, as for example, that the temperatures, reactiontime, and relative amounts of reagents used may be varied, withoutcleparting from the spirit of this invention. We therefore do notpropose limiting the patent granted hereon other than as necessitated bythe prior art.

We claim as our invention:

1. The process of sulfonating an aromatic amino body substantially inortho position to the amino group, which comprises treating the aromaticamino body in an inert organic solvent with sulfur trioxide.

2. The process of sulfonating an aromatic amino body substantially inortho position to the amino group, which comprises treating the aromaticamino body in tetrachlorethane with sulfur trioxide.

the amino group, which comprises treating the aromatic amino body intetrachlorethane with sulfur trioXide and heating the solution to effectsulphonation. 1

5. The process of preparing an ortho sulfo amino aromaticcompound,'which comprises treating an amino aromatic compound inan inertorganic solvent therefor, with sulfur trioxide, heating and refluxingthe mass un- -til the reaction is substantially complete and recoveringthe ortho-sulfo amino compound.

6. The process of preparing an ortho sulfo amino aromatic compound,which comprises treating an amino aromatic compound in tetrachlorethanewith sulfur trioxide, heating and refluxing the mass until the reactionis substantially complete and recovering the ortho sulfo amino compound.V

7 The process of preparing an ortho sul-' pho amino aromatic compound,which comprises treating an amino aromatic compound in tetrachlorethanewith sulphur trioxide, heating the mass until the reaction issubstantially complete, cooling, diluting, rendering alkaline,separating the aqueous solution formed from the tetrachlorethane,acidifying the aqueous solution and salting out the ortho sulpho aminocompound from the acidified solution.

8. The process of preparing 1,3-dimethyl- 4-amino-5-sulpho benzene,which comprises treating meta Xylidine dissolved in tetrachlorethanewith sulphur trioxide. I w

9. The process of preparing 1,3-dimethyl- 4t-amino-5-sulpho benzene,which comprises treating meta Xylidine dissolved in tetrachlorethanewith sulphur trioXide, and heating the mass to approximately boilingtemperatures to effect sulphonation.

10. The process of preparing 1,3-dimethyla-amino-dsulpho benzene, whichcomprises introducing sulphur trioxide into a mass of meta Xylidinedissolved in an inert dry organic solvent and heating the mass to efiectsulphonation.

11. The process of preparing 1,3-dimethyll-amino-5-sulpho benzene, whichcomprises introducing sulphur trioxide into amass of meta Xylidinedissolved in tetrachlorethane andheating the mass under refluxingcondi-" tions to effect sulphonation. of the meta xylidine to1,3-dimethy1-4-amina-5-su1pho benzene.

12. The process of preparing 1-su1fo-2- amino-naphthalene, whichcomprises introducing sulfur trioxide into a mass of beta naphthylaminedissolvedin an inert dry .or-

ganic solvent and heating the mass to effect sulphonation.

13. The process of preparing l-sulfo-Q-amino-naphthalene, Whichcomprises introducing sulfur trioXide into a mass of beta naphthylaminedissolved in tetra-chlor-ethane and

